Methamphetamine (MA) abuse and its associated problems are growing, but little is known about their treatment. Similarities between MA and cocaine suggest that cocaine abuse treatment can provide an excellent starting point for research on MA abuse treatment. Differences in their mechanism of action in animal self-administration studies suggest that selective serotonin reuptake inhibitors, while not effective in reducing cocaine use, may yet work to reduce MA abuse. Sertraline is one such agent. Contingency management (CM) offers a clearly defined behavioral strategy that has been shown to produce significant reductions in cocaine use, and thus appears to have promise for MA abuse treatment. The proposed study uses a 2X2 factorial design to evaluate sertraline and CM, alone and in combination, in double-blind placebo-controlled fashion as treatment for 220 MA abusers, meeting DSM-IV criteria for abuse or dependence and volunteering for treatment at the Matrix clinic in Rancho Cucamonga, California. Ss will be randomly assigned to one of four experimental conditions (sertraline- CM; sertraline-no CM; placebo-CM; placebo-no CM) and treated for 12 weeks. In addition, Ss will participate in a thrice weekly manualized counseling program. Sertraline will be titrated to 100mg/day, and the CM procedures will be identical to those described by Higgins and colleagues in their cocaine research. Outcome measures will include drug use, treatment retention, psychosocial functioning, HIV risk behavior and adverse medical events. Follow up will be conducted at 6 and 12 months post-admission. The research team has extensive experience in conducting medication and behavioral evaluations for stimulant treatment. Completion of this 4 year project will provide relevant information on several promising treatment strategies for MA abuse/dependence.